Like the rest of the Microsoft Office unit, the Office Web Apps team seems to be on a path to deliver more new updates more frequently.
This week, the Web Apps team (which also internally goes by WAC, or Web Applications Companion) blogged about some of the new features coming to Office Web Apps "over the next year and beyond." These include official support for Chrome on Android tablets and real-time co-authoring (instead of "same time" authoring), starting with PowerPoint Web App.
Microsoft executives also previously have said that Yammer integration will be coming to Office Web Apps, too, starting this fall. Specifically, the Softies said to expect integration of the Office Web Apps' editing/co-editing of Word, PowerPoint, and Excel documents with Yammer.